Is your mind blown yet? No? Well then let's continue the exploration into the blatant identity theft of fruits. In our Plant Structure Lab this week, we examined a plethora of fleshy and dry fruits. Using the "Key to Common Fruits" handout, our job was to identify the imposters with misleading common names. For example, that ballpark favorite, the peanut, isn't actually a nut at all. It is a legume in the family, Fabaceae. That's right, the same family as the broad bean we looked at in earlier labs. This peanut has marginal placentation because the ovules develop in rows near the margin on the placenta formed along the ventral suture. The pericarp of the peanut is the dehiscent outer shell that we crack to get to the yummy fruit inside. It is a fusion of the exocarp, mesocarp, and endocarp. Moving on to the fleshy fruits, we dissected a beautiful, juicy, orange. In the orange, or Citrus sp., we were able to see clearly the exocarp, endocarp, and mesocarp. The endocarp of the orange is chock full of juice-filled hairs that are used for food storage for the embryo. The mesocarp has many oil filled sacs, from which that wonderful citrus smell comes from. The exocarp is the outer peel that protects the embryo and endosperm. Surprise, surprise, the simple fruit of the orange turned out to be a type of berry, called a hesperidium. The orange shows axile placentation because the placentae develop from the central axis which corresponds to the confluent margins of carpels. On Thursday in lab, we examined a series of cross-sections of Tilia stems of different ages, looking for signs of secondary growth. Secondary growth occurs in most seed plants, like dicots and gymnosperms, but very rarely in monocots as their vascular tissue cannot form into a ring. The lateral meristems, vascular cambium and cork cambium, are responsible for the production of secondary xylem and secondary phloem. In woody plants, this produces wood and bark. In non-woody plants, secondary growth can result in thickened, modified stems such as potatoes. Now my challenge to you: can you name what types of fruits the following are? Are they dry or fleshy? Dehiscent or indehiscent? What type of placentation, locule number? Blog posted by: Holly Giorgio-Dundon
1 Comment
7/22/2021 03:19:27 am
Very much appreciated. Thank you for this excellent article. Keep posting!
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